Struggling with dependent text or list display in cell

Hi - thanks for reading

I'm not sure if this is possible but I'd like to get the following to work:
- Cell A1 contains a small pick from list
- The response in A1 triggers either of the following in B1
1) text ('Not applicable' for example); or
2) a different pick from list.

Have tried everything I can think of so any help at all would be appreciated!

Thanks

Jon